manpagez: man pages & more
man grdpmodeler(1)
Home | html | info | man
grdpmodeler(1)                        GMT                       grdpmodeler(1)




NAME

       grdpmodeler - Evaluate a plate motion model on a geographic grid


SYNOPSIS

       grdpmodeler agegrdfile  -Erot_file -Sflags [  -Fpolygonfile ] [  -Gout-
       grdfile ] [  -Tage ] [  -V[level] ] [ -bbinary ] [ -dnodata ] [ -hhead-
       ers ] [ -:[i|o] ]

       Note:  No  space  is allowed between the option flag and the associated
       arguments.


DESCRIPTION

       grdpmodeler reads a geographical age grid and a plate motion model  and
       evaluates  one  of  several model predictions. Optionally, the user may
       supply a clipping polygon in multiple-segment format;  then,  only  the
       part of the grid inside the polygon is used to determine the model pre-
       diction; the remainder of the grid is set to NaN.


REQUIRED ARGUMENTS

       ingrdfile
              Name of a grid file in geographical (lon, lat) coordinates  with
              ages in Myr.

       -Erotfile
              Give  file  with rotation parameters. This file must contain one
              record for each rotation; each record must be of  the  following
              format:

              lon lat tstart [tstop] angle [ khat a b c d e f g df ]

              where  tstart  and  tstop  are  in  Myr and lon lat angle are in
              degrees. tstart and tstop are the ages of the old and young ends
              of  a  stage. If tstop is not present in the record then a total
              reconstruction rotation is expected and tstop is implicitly  set
              to  0  and should not be specified for any of the records in the
              file. If a covariance matrix C for the rotation is available  it
              must  be  specified  in  a  format using the nine optional terms
              listed in brackets. Here, C = (g/khat)*[ a b d; b c e; d e  f  ]
              which  shows  C  made up of three row vectors. If the degrees of
              freedom (df) in fitting the rotation is 0 or not given it is set
              to  10000. Blank lines and records whose first column contains #
              will be ignored. You may prepend a leading + to the filename  to
              indicate  you wish to invert the rotations.  Alternatively, give
              the filename composed of two plate IDs  separated  by  a  hyphen
              (e.g.,  PAC-MBL)  and we will instead extract that rotation from
              the GPlates rotation database. We return an error if  the  rota-
              tion cannot be found.

       -Sflags
              Type  of  model  prediction(s). Append one or more items: choose
              from a for plate motion azimuth,  d  for  great-circle  distance
              between  current location and its origin at the ridge (in km), s
              for plate motion model stage ID (1 is  youngest),  v  for  plate
              motion  rate (in mm/yr), w for plate rotation rate (degree/Myr),
              x for change in longitude relative to location of  crust  forma-
              tion,  y  for  change  in latitude relative to location of crust
              formation, X for longitude of crust formation, and Y  for  lati-
              tude  of  crust formation.  If no arguments are given we default
              to all [adsvwxyXY].


OPTIONAL ARGUMENTS

       -Fpolygonfile
              Specify a multisegment closed polygon file  that  describes  the
              inside area of the grid where the model should be evaluated; the
              outside will be set to  NaN  [Default  evaluates  model  on  the
              entire grid].

       -Goutgrdfile
              Name of output grid. This is the grid with the model predictions
              given the specified rotations. Note: If you specified more  than
              one  model prediction in -S then the filename must be a template
              that contains the format %s; this will be replaced with the cor-
              responding  tags  az,  dist, stage, vel, omega, dlon, dlat, lon,
              lat.  If the -G option is not used then we create no  grids  and
              instead  write  lon,  lat,  age, predictions records to standard
              output.

       -Tage  Use a fixed age for model evaluation (i.e., override the ages in
              the age grid). This lets you evaluate the model at a snapshot in
              time.

       -V[level] (more a|)
              Select verbosity level [c].

       -bi[ncols][t] (more a|)
              Select native binary input. [Default is 2 input columns].

       -d[i|o]nodata (more a|)
              Replace input columns that equal nodata  with  NaN  and  do  the
              reverse on output.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more a|)
              Skip or produce header record(s).

       -^ or just -
              Print  a  short  message  about  the syntax of the command, then
              exits (NOTE: on Windows just use -).

       -+ or just +
              Print an extensive usage (help) message, including the  explana-
              tion  of  any  module-specific  option  (but  not the GMT common
              options), then exits.

       -? or no arguments
              Print a complete usage (help) message, including the explanation
              of all options, then exits.


GEODETIC VERSUS GEOCENTRIC COORDIINATES

       All  spherical  rotations  are applied to geocentric coordinates.  This
       means that incoming data points and grids are considered  to  represent
       geodetic  coordinates and must first be converted to geocentric coordi-
       nates. Rotations are then applied, and the final  reconstructed  points
       are  converted back to geodetic coordinates.  This default behavior can
       be bypassed if the  ellipsoid  setting  PROJ_ELLIPSOID  is  changed  to
       Sphere.


EXAMPLES

       We will use a grid with Pacific crust ages (pac_age.nc), a plate motion
       model (Pac_APM.d), and a polygon  that  contains  the  outline  of  the
       present  Pacific  plate (pac_clip_path.d). To evaluate the plate motion
       azimuths at the present time for the Pacific, try

              gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
                              -Gpac_dir_0.nc -Sa -T0

       To determine the changes in latitude  since  crust  formation  for  the
       entire Pacific, try

              gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
                              -Gpac_dlat.nc -Sy

       To  determine  the  plate  motion velocities in effect when the Pacific
       crust was formed, try

              gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
                              -Gpac_vel.nc -Sv

       To determine how far the crust has moved since formation, try

              gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
                              -Gpac_dist.nc -Sd

       To save the coordinates of the crustas formation to separate grids, try

              gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d \
                              -Gpac_origin_%s.nc -SXY

       To repeat the same exercise but save output lon,lat,age,xorigin,yorigin
       to a table, use

              gmt grdpmodeler pac_age.nc -EPac_APM.d -V -Fpac_clip_path.d -SXY > origin.txt


NOTES

       GMT   distributes   the   EarthByte   rotation   model    Global_Earth-
       Byte_230-0Ma_GK07_AREPS.rot.  To use an alternate rotation file, create
       an environmental parameters named GPLATES_ROTATIONS that points  to  an
       alternate rotation file.


SEE ALSO

       backtracker(1), gmtpmodeler(1), grdrotater(1), grdspotter(1),
       hotspotter(1), originator(1), rotconverter(1)


COPYRIGHT

       2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe



5.4.2                            Jun 24, 2017                   grdpmodeler(1)

gmt5 5.4.2 - Generated Thu Jun 29 07:41:12 CDT 2017
© manpagez.com 2000-2021
Individual documents may contain additional copyright information.